Adinotherium (meaning "not Deinotherium") is an extinct genus of Toxodontidae, large bodied hoofed ungulates which inhabited South America during the Miocene living from 17.5—11.61 million years ago and existed for approximately 5.89 million years.
Adinotherium was an extinct mammal of the family Toxodontidae, a representative of the South American fauna of the Miocene epoch.
On the whole, resembled a smaller version of its cousin Toxodon.

The forefeet of Adinotherium were longer than those of Toxodon, so that the height at the shoulders and the pelvis were equal, which facilitated running. There are several types of Adinotherium species: Adinotherium ferum and Adinotherium ovinum. The largest of them - Adinotherium ovinum, reaching 1.5 meters in length, with an increase of about 80 cm and weighing 120 kg. The 1.5 metres (4.9 ft) long animal looked like a smaller version of its rhinoceros-like relative Toxodon. Its front legs were somewhat longer than those of its relatives, making its hip and shoulder height about equal. A small horn atop Adinotherium's skull may have played a role in the mating season.